MALLOPHAGA FROM BIRDS 459 



nigroficti, abundant on terns and gulls and normally peculiar 

 to these ocean birds was taken also on Gcospiza, Cafnarhynchus , 

 JVesojnijnus and Progne. The first cases of this kind met with 

 in working over the collection were attributed to mistakes in the 

 collectors' records, or to straggling after death when the birds' 

 bodies were in occasional contact in the game bag or on the 

 skinning table. But the repeated occurrence of these extra- 

 ordinary conditions and the testimony of the collectors soon 

 revealed the true cause of this unusual distribution. We have 

 to do with an abnormal phase of normal straggling ! On the 

 rocks of the islands maritime and land birds sit closely huddled, 

 actual contact of the bodies often occurring. Migration is 

 easily effected, and thus a parasite species {Colpocephalufn 

 uncifertmi Keel) normally peculiar to pelicans finds its way to a 

 warbler (or honeycreeper), Certhidea. Thus are explained the 

 large number of unusual and startling instances in the host dis- 

 tribution of the Galapagos Island Mallophaga. 



Certain facts of interest connected with the parasites found 

 on the bird genera peculiar to the archipelago, should be 

 touched on. Geosfiza fiiliginosa has a total of twenty Mallo- 

 phagous species credited to it, the largest recorded list of Mallo- 

 phaga from any bird species. Four or more parasitic species 

 are recorded from each of i8 of the 34 bird species from which 

 Mallophaga were taken ; a condition unique in the records of 

 collections of Mallophaga. This condition, of abundant para- 

 sitism, is, of course, also due to the unusual facility of migration 

 (or normal straggling) afforded by the forced gregarious habits 

 of the islands' birds. A fair number of the bird species peculiar 

 to the archipelago are infested by parasitic species not hitherto 

 known, and thus will lend a special interest to any collections 

 of Mallophaga which may be made from birds of the west coast 

 of South and Central America, the region from which the bird 

 fauna of the islands has been derived. It is of interest to note 

 the marked commonness of parasitic species to the genera 

 Geospiza and CamarhyncJms, thus lending weight to the belief 

 in their very near relationship. However there is at present, 

 as already said, little of real value to be got from such specu- 

 lation. A considerable number of the species in this collection 



